Polaris 300 Xpress 2 stoke problem

OK well after redoing the top end due to oil pump failure he opted to mix gas, this should have been an easy redo as we have done many before. I finished it up put the charger on battery it was pretty low, and fired right up, it was late so I ran it for a few minutes. The next day it wouldn't do anything so we thought cylinder walls got washed maybe. from trying to start it, so we put a bit a of oil in the spark plug hole firesd up smoked alot :) then ran fine I ran it around for 20 minutes probably, shut off turned right back on. Then Sunday it would do anything again. we tried everything, I took off exhaust thought maybe it was plugged it, it started with exhaust off too loud so we shut her down. tried it again and it seemed like it ran out of gas, that is after the carb rebuilt and fresh gas. We put air into the intake with a air hose and fired up. What the heck could the problem be, the only left we are thinking is crank seals went out of it. It is an 96' model.

Any help would be great thanks in advance.

I'd go here: http://www.gen3usa.com/ , and ask the question. These guys are the experts on those quads.